U.S. Pat. No. 6,375,096 discloses a two component spray gun and nozzle attachment, the abstract recites,                The present invention relates to polyurethane foam spray guns and disposable, attachable nozzles. The spray gun has at least two barrels and metering chambers containing continuous passageways defined by inner bores. Each inner bore can have at least one ramp-shaped slot for controlled metering of a resin. Within each barrel and metering chamber is a plunger. At the front end of the plunger but not the tip is an O-ring that aids in the control of the metering of each resin. At the mid-section of the plunger is at least one O-ring that aids in the prevention of leakage within the spray gun. Both the plunger tip and the discharge opening of each barrel/metering chamber are narrowed/conical. The nozzle contains a one-way valve to prevent the crossover of the resins. The nozzle's tip has different shapes depending on the structure of the foam product desired.        
Patent application Ser. No. 7,717,357 discloses a Method for rapid insulation of expanses, the abstract recites,                A process for cost-effectively and rapidly insulating a desired surface with spray foam insulation is described which includes the application of a polyurethane foam dispensed through heated conduits into a dispensing gun having a nozzle with essentially planar divergent lips having a triangular prism opening, the lips of the nozzle diverging at an angle of between about 5 and 35° inclusive, more preferably between 8 to 15° inclusive, most preferably 10 to 12° inclusive, thereby achieving application rates which are in excess of 70 Ft2/min, and optimally in excess of 100 Ft2/min.        
Portable low pressure two part polyurethane spray foam is primarily supplied in pressurized canisters that when empty are disposed of, or they are supplied in refillable canisters that are pressurized on the jobsite and shipped back to the supplier to be refilled when empty. These portable systems would benefit from the ability to be refilled in the field.
Portable low pressure two part polyurethane spray foam systems are supplied with A & B chemicals that have different viscosities at different temperatures and therefore could benefit from being able to check the flow ratios and adjust them as necessary.
Portable low pressure two part polyurethane spray foam systems are supplied with a disposable spray gun that utilizes disposable tips. A dozen tips or more are supplied with each system. This is because the static mixers clog up within 20-30 seconds of non-use. These systems could benefit from a replaceable tip that can be cleaned and reused.
There exists a need for a spraying system, comprising of two triggers that may connect with each other, serving the purpose of checking the ratio of fluid spraying from one chamber or another so that the user may determine if the system is dispensing chemicals at the proper ratios before spraying, and them may adjust the spray gun accordingly.
There exists a need for canisters that may be refilled in the field, therefore eliminating process of shipping canisters to be refilled, or disposing of them.
There also exists a need for a means of mixing product or foam by means of a vortex mechanism adjacent to the nozzle.
There is also a need for a spray gun that has an attachable nozzle that may be attached to the tip and said nozzle has a vortex mechanism that is air induced and is capable of mixing substances from two chambers into one substance and then spraying the mixed material.